Now Completely Reversible

Just when I thought brioche couldn't get any better, it has. Introducing:

Reversible Increases and Decreases for One-Pass Brioche.

This is magic. This is groundbreaking. This actually has me excited to rip out a month's work.
This is so much harder to explain than regular increases and decreases that I made videos. I know I've been saying I would for a while. Now you have them.

I'll start with why I'm so stupidly excited (other than that I get like that pretty easy.).
With regular brioche, the increase or decrease is made with both knit and purl columns in the same stitch. While this gives a nice branching effect on the right side, on the wrong side, the columns suddenly stop and start, and the true pattern isn't shown.

Half-made Interweave hat, showing both right and wrong sides.
Regular increases and decreases start and stop abruptly on the wrong side (top).

With the reversible increases and decreases, the stitches are rearranged and each column is worked separately, to give the exact same effect on both sides. So the pattern shows true on both sides on the piece making it truly a reversible fabric. Magic!

Half-made Interweave hat showing both sides.
Reversible increases and decreases are the same on both sides of the fabric.

Then we're on to the exciting stuff. Increases. You'll need a cable needle or a crochet hook, just something to stash a stitch safely while you knit just one other.

Here's the complicated version:
Knit, do not drop the old stitch, transfer it to the cable needle and keep in front.
Move yarns as normal to prep for a purl. Purl the next stitch, again don't drop the old stitch. Draw out the new stitch and drop it to the back. Slip the original purl stitch to the left needle.
Move knit yarn to back, slip stitch off the cable needle to the left needle.
Move knit yarn to front, place loose purl stitch back on left needle. Check it's mounted correctly with the loos tail to the back of the needle, and tighten it up.
Your yarns should both be in front, a knit and a purl column have been worked and the next stitch is a knit.

And finally decreases. The process is slightly different for each, but pretty obvious when you look at which way you want it to go. It is possible to work these with ssk, k2tog etc, but I find it absurdly hard with four pieces of yarn involved. Working the stitches individually makes it less likely I'm going to drop something and easier to remember which way the decrease will lean. Bonus for righties: easier to mirror if you want to!

Again, complicated version, Decrease Left:
Knit, slip the purl stitch to the cable needle and keep at the back.
Slip the new knit stitch back to the right needle and pass the next knit stitch over.
Slip new stitch back to left needle.
Place the cabled stitch back on to the right needle. Make sure your yarns are set up for a purl stitch and purl.
Reverse the mount of the next purl stitch by slipping knit wise, then back to the right needle purl wise. Slip the new stitch back to the right needle as well, then pass the reversed stitch over.
Slip new stitch back to left needle.
Your yarns should both be in front, two knit and two purl columns have been worked and the next stitch is a knit.

Decrease Right:
Slip knit stitch knit wise, slip the purl stitch to the cable needle and keep at the back. 
Knit next knit stitch and pass slipped stitch over. 
Move yarns as normal to prep for a purl.
Slip cabled stitch to the left needle, purl the next stitch then pass cabled stitch over. 
Your yarns should both be in front, two knit and two purl columns have been worked and the next stitch is a knit.

I hope you enjoy these techniques as much as I do, and please get back to me with any feedback or questions.

Cheers!